Indwelling Neural Implants: Strategies for Contending with the In Vivo Environment (Frontiers in Neuroengineering Series)

INDWELLING NEURAL IMPLANTS: STRATEGIES for CONTENDING with the IN VIVO ENVIRONMENT......Page 3
Contents......Page 6
Series Preface......Page 8
Preface......Page 9
Acknowledgments......Page 11
Editor......Page 12
Contributors......Page 13
Part I......Page 15
1.1 INTRODUCTION AND OVERVIEW......Page 16
1.3.1 INITIAL EVENTS......Page 19
1.3.2 LATER EVENTS (CENTRAL NERVOUS SYSTEM [CNS] VERSUS NON-CNS)......Page 21
1.4 REPAIR (DAYS TO WEEKS)......Page 25
1.4.1.1.1 Partial-Thickness Skin Repair......Page 26
1.4.1.1.2 Stabilized Bone Repair......Page 27
1.4.1.1.3 Peripheral Nervous System (PNS) Repair......Page 29
1.4.1.2.2 Full-Thickness Cutaneous Tissue Repair......Page 30
1.4.1.2.2 Bone Repair......Page 31
1.4.2 CNS REPAIR (GLIOSIS)......Page 33
1.4.2.1 Purpose of the Glial Scar......Page 34
1.5.1.1.1 Partial-Thickness Cutaneous Tissue Remodeling......Page 37
1.5.1.1.3 PNS Remodeling......Page 38
1.5.1.2.1 Full-Thickness Cutaneous Tissue Remodeling......Page 40
1.5.1.2.2 Unstabilized Bone Remodeling......Page 41
1.5.2 CNS REMODELING......Page 42
1.6 CONCLUSION......Page 43
REFERENCES......Page 44
Part II......Page 52
CONTENTS......Page 53
2.1.3 CONSIDERATION OF NEURONAL DAMAGE......Page 54
2.2.1 THE IMPORTANCE OF PROXIMITY FOR STIMULATION......Page 55
2.2.2 EFFECT OF NEURONAL DEATH ON STIMULATION INPUT–OUTPUT PROPERTIES......Page 56
2.3.1 PASSIVE PROPERTIES......Page 59
2.3.2.1 Electrochemistry of the Electrode–Electrolyte Interface......Page 61
2.3.2.2 Activity-Dependent Changes in Neuronal Excitability......Page 62
2.3.2.3 Stimulation-Induced Neuronal Injury......Page 63
2.4.1 PASSIVE PROPERTIES......Page 64
2.4.2.2 Autopsy Findings......Page 65
2.4.2.3 Charge Density Limits......Page 67
2.4.2.4 Performance Considerations......Page 68
ACKNOWLEDGMENTS......Page 69
REFERENCES......Page 70
3.1 INTRODUCTION......Page 74
3.2 OVERVIEW OF THE SOURCES OF HEAT IN A CORTEX BMI (CBMI)......Page 75
3.2.1 SENSING CORTICAL BRAIN ACTIVITY-AMPLIFIERS......Page 76
3.2.2 SPIKE ACQUISITION AND PROCESSING......Page 78
3.2.3 TELEMETRY......Page 79
3.2.4 POWERING THE IMPLANT......Page 80
3.3 HEAT GENERATED IN A CBMI IMPLANT......Page 81
3.3.1 HEAT DISSIPATION IN THE BODY......Page 82
3.3.3 INSULATION......Page 86
3.3.4 BMI-RELATED THERMAL STUDIES......Page 87
3.4 EFFECT OF HEAT ON TISSUE......Page 88
3.4.1 BRAIN TISSUE RESPONSE TO HEATING......Page 89
3.5 RECOMMENDATIONS......Page 91
3.5.3 RECOMMENDATION 3: SEPARATE POWER TRANSMISSION COILS FROM OTHER IMPLANTED METALLIC OBJECTS......Page 92
3.5.4 RECOMMENDATION 4: MINIMIZE THE POWER CONSUMPTION IN DEVICES IN CLOSE PROXIMITY TO THE BRAIN......Page 93
REFERENCES......Page 94
Part III......Page 98
CONTENTS......Page 99
4.1.1 RELATIVE ADVANTAGES OF IN VITRO MODELS......Page 100
4.1.2 IN VITRO MODEL LIMITATIONS......Page 101
4.1.3 THE VALUE OF IN VITRO ANALYSIS TO EXPLAIN IN VIVO OBSERVATIONS: A CASE STUDY......Page 102
4.2 TYPES OF MODELS......Page 103
4.2.1 CELL LINES......Page 104
4.2.1.2 Neuronal Cell Lines......Page 105
4.2.1.4 Microglia Cell Lines......Page 107
4.2.2 PRIMARY CELLS......Page 109
4.2.2.1 Single Cell Type Primary Cultures: Primary Neurons......Page 110
4.2.2.3 Single Cell Type Primary Cultures: Primary Microglia......Page 112
4.2.2.4 Single Cell Type Primary Cultures: Primary Astrocytes......Page 113
4.2.2.5 Primary Cell Coculture......Page 114
4.2.2.6 Multicell Primary Cultures: An In Vitro Model of Glial Scarring......Page 115
4.2.3.1 Brain Slices: Complexity Approaching In Vivo......Page 119
4.2.3.2 Brain Slices: Biocompatibility Studies......Page 120
4.3 CONCLUSIONS......Page 129
REFERENCES......Page 130
CONTENTS......Page 134
5.1 INTRODUCTION......Page 135
5.2.1.1 Diffusion Experiments......Page 137
5.2.1.3 Fluorescence Imaging of Samples......Page 139
5.2.1.4 Quantitative Image Analysis......Page 140
5.2.1.5 Data Processing......Page 141
5.2.1.6 Gel Diffusivity Characterization Experiments......Page 142
5.2.1.7 Evaluation of In Vivo Diffusivity Properties: Central Nervous System (CNS)–Extracellular Space (ECS) Solute Diffusion Modeling......Page 143
5.3.1 GEL DIFFUSIVITY CHARACTERIZATION EXPERIMENT......Page 146
5.3.2 QUANTITATIVE FLUORESCENCE PROFILE (QFP) ANALYSIS OF CNS TISSUE ACCESS DEVICE (TAD) IMPLANT GROUPS......Page 148
5.3.3.3 Simulation Analysis of Control and Experimental Group 30-Minute Probe Distributions......Page 151
5.4 DISCUSSION......Page 155
ABBREVIATIONS......Page 161
REFERENCES......Page 162
Part IV......Page 166
CONTENTS......Page 167
6.1 INTRODUCTION......Page 168
6.2.1.1 Vascular Damage......Page 170
6.2.1.2 Mechanical Injury......Page 173
6.2.1.3.1 Cytokines......Page 174
6.2.1.3.2 Proteases......Page 177
6.2.2.1 Frustrated Phagocytosis......Page 178
6.2.2.2 Mechanical Strain......Page 179
6.3 MOLECULAR STRATEGIES TO MINIMIZE THE ABOVE RESPONSES......Page 181
6.3.2 STRATEGY II: ATTENUATING INFLAMMATION......Page 182
6.3.3 STRATEGY III: PROMOTING MIGRATION AND SURVIVAL OF NEURONS AND NEURITES......Page 184
REFERENCES......Page 186
7.1 INTRODUCTION......Page 192
7.2 OVERVIEW OF NEURAL PROSTHETIC DEVICES......Page 193
7.3 RECORDING SITE–NEURON INTERFACE......Page 195
7.4 BIOMATERIAL COATINGS ON IMPLANTED ELECTRODES......Page 196
7.4.1 INCORPORATION OF BIOLOGIC SPECIES INTO CONDUCTING POLYMERS......Page 203
7.4.2 HYDROGELS......Page 205
7.4.3 NANOTUBES......Page 210
7.4.4 HYBRID LIVE CELL-CONDUCTING POLYMER COATINGS FOR NEURAL ELECTRODES......Page 212
7.4.5.1 PEDOT and Counter-Ions......Page 217
7.4.5.2 PEDOT Degradation......Page 219
7.4.6 BIOLOGICAL CONJUGATED POLYMERS: MELANINS......Page 220
ACKNOWLEDGMENTS......Page 224
REFERENCES......Page 225
8.1 INTRODUCTION......Page 235
8.1.1 TRAUMATIC INJURY IN THE CENTRAL NERVOUS SYSTEM (CNS): BRAIN AND SPINAL CORD......Page 236
8.2.1 BLOOD–BRAIN BARRIER (BBB) AND BLOOD–SPINAL CORD BARRIER (BSCB)......Page 237
8.2.2 DUAL ROLE OF INFLAMMATION IN TRAUMATIC CNS INJURY......Page 238
8.2.3 GLIAL SCAR LIMITS REGENERATION......Page 239
8.3 NEUROPROTECTION AND NEUROREGENERATION TREATMENT STRATEGIES......Page 240
8.3.1 DRUG DELIVERY TO THE INJURED CNS FOR NEUROPROTECTION AND NEUROREGENERATION......Page 241
8.3.2 CELL DELIVERY TO THE INJURED CNS FOR NEUROPROTECTION AND NEUROREGENERATION......Page 243
8.3.3 TISSUE ENGINEERING AND BIOMATERIAL STRATEGIES IN THE INJURED CNS......Page 246
8.4 FUTURE OUTLOOK: OPPORTUNITIES AND CHALLENGES......Page 248
REFERENCES......Page 249